Field of the Invention
The present invention relates to an ophthalmologic apparatus and a method of controlling the same, and more particularly, to a fundus image acquiring apparatus for acquiring an image of a minute site of a fundus of a subject at high resolution.
Description of the Related Art
There is known a technology for detecting a wavefront aberration of a reflected beam of light projected on a fundus by using a wavefront sensor disposed in a position approximately conjugate with a pupil of an eye to be inspected, and correcting an aberration of the eye to be inspected which is detected as the wavefront aberration by using an aberration correcting device. A research is also made to acquire an image of a minute site of a fundus at high resolution by utilizing the aberration correcting technology, and to use information on shapes and densities of photoreceptor cells, flow of blood cells, run of nerve fiber layers, damage, and the like in diagnosis.
When an image of a fundus is acquired while correcting an aberration, an image having a resolving power of several micrometers is obtained. Because this optical system has a high NA, a depth of field is shallow, and hence the resulting image is limited to information in the range of several tens of micrometers in a depth direction. As a result, a clinical value is high because only an image of an interested layer can be observed. However, a clinically interested tissue within a retina has a gap of about several hundreds of micrometers in the depth direction from a pigment epithelium to a nerve fiber layer. Therefore, in order to observe the tissues, refocus is necessary on the individual tissues or layers. In addition, because stereoscopic information on a thickness of each layer and the like is also useful in the diagnosis, it is also demanded to form three-dimensional imaging information or a three-dimensional image which is displayed with a precise size.
Japanese Patent Application Laid-Open No. 2010-259543 discloses a technology for obtaining three-dimensional information on a subject by using a confocal microscope. Because, with this technology, the stereography is carried out while a stage on which a subject is placed is quantitatively moved with respect to a fixed optical system, precise stereoscopic information is obtained. However, the fundus is required to be imaged through an optical system of the eye ball. Therefore, even when the eye to be inspected as the subject is moved similarly to the case of the technology disclosed in Japanese Patent Application Laid-Open No. 2010-259543, the optical position of the subject cannot be precisely changed. In addition, there is a problem in that, because a refractive error, beat, accommodative microfluctuation, a motion of the head, and the like are added to the eye to be inspected, it is difficult to carry out the stereography having precise dimension information in a depth direction.